Pride of place must go to the Olmec, the first technologically complex culture in the hemisphere. Appearing the the narrow waist of Mexico about 1800 BC, the lived in cities and towns centered on temple mounds. Strewn among them were colossal male heads of stone, many six feet tall or more, with helmet-like headgear, perpetual frowns, and somewhat African features, the last of which has given rise to speculation that Olmec culture was inspired by voyagers from Africa. The Olmec were but the first of many societies that rose in Mesoamerica in this epoch. Most had religions that focused on human sacrifice, dark by contemporary standards, but the economic and scientific accomplishments were brights. They invented a dozen different systems fo writing, established widespread trade networks, tracked the orbits of the planets, created a 365-day calendar, more accurate than its contemporaries in Europe, and recorded their histories in accordion-folded books of fig tree bark paper.